Position Isomerism
Structural isomerism arising from a functional group occupying different positions on the same carbon skeleton.
Unit
Dimensionless
In depth
The skeleton and the group are unchanged; only the attachment point moves. Position isomers usually have similar but distinguishable properties, and the difference can be decisive chemically — a primary alcohol oxidises to an acid while its secondary isomer gives a ketone.
Examples in the real world
Propan-1-ol and propan-2-ol; but-1-ene and but-2-ene; 1,2- and 1,4-dichlorobenzene.